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sean-cattee avatar image
sean-cattee asked

Appropriate MPPT for 4x panels on 24V system?

My question is that I'm not sure what setup would be best if I have 4 of the following panels:

https://voltaconsolar.com/solar-panel/mono-crystalline/410w-mono-facial-solar-panel-rs41-410m-e3.html

The online calculator suggests at 2S2P I should be using a 150/70 for a 24V system.

I have bought a Cerbo, and would like to connect the solar controller to it, is there a particular type (E.G Blue solar/Smart solar) that I would need for this?


Thanks in advance - I'm new to all this stuff, I figured it's best to ask those who know rather than make a costly mistake.

MPPT Controllerscerbo gxsolar sizing
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Alexandra avatar image
Alexandra answered ·

@Sean Cattee

You will also need a ve direct to ve direct cable to connect the cerbo to the mppt.

The smart solar allows you to program it with your phone.

The blue solar you will need either the ve direct to bluetooth dongle to program it or the ve direct to usb (with laptop or otg) you can also use the ve direct to usb to connect to the cerbo.

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sean-cattee avatar image sean-cattee commented ·
Thanks a ton for the Cerbo connection diagram, that looks invaluable to say the least!
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astrayan avatar image
astrayan answered ·

Don't be surprised if you only get 48-52A. You are charging up to 28.8V, and the panels will be 85% efficient when hot, after a few years.

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sean-cattee avatar image sean-cattee commented ·
Is there a particular reason I would be limited to 48-52A? I'm aware that heat hurts panel efficiency etc.

Would I be correct in saying that MPPT is enough to handle those panels? Just trying to make sure I don't make an oversight.


Thanks.

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Alexandra avatar image
Alexandra answered ·

@Sean Cattee

Irradiance and temperature will affect what the panels yeild. Higher panel temps you see lower voltages, colder means higher. And sunshine is not a shiney as you think ;) .... So you may see more or less depending on conditons.

I think @Astrayan is getting a bit ahead of things here.

I have a 150/70 on a 24 system and I see the 70A full output often.

Power (or wattage) is voltage x amps...

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sean-cattee avatar image sean-cattee commented ·
As a resident of England I don't have particularly high expectations, if I clock in over 1kw I'll be a happy bunny.

I recently found that 12/24v MPPTs exist in the Victron range and they're significantly cheaper, so that's a bonus! I have no expectations to go higher than 24v due to the cost of batteries.

I figured;

410w × 4 = 1640w

1640w / 24v = 68.3A

1640w / 28.8v = 56.9A

Not accounting for inefficiency, these are the "perfect" conditions I'll never achieve, so in theory they're the worst case scenario in terms of peak power which is well within a 150/70's capabilities.


Thanks once more :)

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